1. Field of the Invention
The present invention relates to a cartridge driving mechanism of a camera which rotates a spool shaft of a cartridge loaded and, more particularly, to a mechanism for preventing a loading mistake attributed to an eccentricity of the spool shaft, etc.
2. Related Background Art
U.S. Pat. No. 4,832,275 discloses the following film cartridge.
This cartridge is constructed in such a way that a film, accommodated in a body while being wound on a spool shaft, is fed out of the body by causing forward rotations of this spool shaft with a driving member of a camera and rewound inwardly of the body by causing reverse rotations thereof. Then, even the tip of the film is accommodated in the body. This type of cartridge is simple to deal with, because the film tip is not exposed to the outside, and there is no possibility in which the film is incautiously pulled out of the cartridge. When loading such a cartridge into the camera, there is eliminated a necessity for such an operation as to pull out the film with a hand and wind it on a take-up spool of a camera as done in the conventional cartridge. Hence, a system (hereinafter referred to as a drop-in load system) is convenient, wherein a cartridge loading hole is formed in the bottom surface of camera, and the cartridge is loaded in the vertical direction via the loading hole.
By the way, rotating the spool shaft of the cartridge loaded by such a drop-in load system involves a step of engaging the spool shaft with a driving member on the camera side. If this engagement is not correctly performed, it is impossible to feed the film.
However, in the above-mentioned cartridge, as depicted in FIG. 1 of foregoing U.S. Pat. No. 4,832,275, the cartridge body is divided into two units (because of its being made of synthetic resin). Especially, a member for holding the spool shaft is divided into two parts. For this reason, it is difficult to accurately hold a central position of the spool shaft with respect to the body. A large fluctuation in the central position of the spool shaft is consequently caused during manufacture. As described above, if the central position of the spool shaft fluctuates largely, the center of the driving member of camera does not coincide with the center of the spool shaft, and they do not engage with each other when loading the cartridge into the camera by the aforementioned drop-in system. There exists a great possibility in which the film can not be fed.
As a measure for preventing this, it can be considered to give a degree of freedom by making an outside diameter of the engaging part of the driving member smaller by an eccentricity presumed than an inside diameter of the engaging recess of the spool shaft. If the outside diameter of the engaging part is made too small, however, the engagement thereof may not be originally performed. This creates to a possibility in which the rotations of the driving member can not be transmitted to the spool shaft. In this case, it is also impossible to feed the film.